title: Dental composite materials containing carolacton inhibit biofilm growth of Streptococcus mutans.
abstract: OBJECTIVE
  Caries adjacent to restorations is one of the main causes for restoration replacement. Antimicrobial substances incorporated into dental materials would potentially be able to reduce secondary caries initiation and progression. This study investigated biofilm growth of Streptococcus mutans UA159 on the surface of composite materials containing the biomolecule carolacton compared to materials containing chlorhexidine (CHX) and triclosan.
  
  
  METHODS
  Biofilm inhibition was investigated by counting colony forming units (CFU), viability staining (Life/Dead), and real-time quantitative PCR.
  
  
  RESULTS
  First, the antimicrobial substances were added to the cultivation medium at 2.5 μg/ml (0.0002%) and 0.25 μg/ml (0.00002%). CHX eliminated bacterial growth and biofilm formation completely. Triclosan was effective at 2.5 μg/ml, but at 0.25 μg/ml biofilm mass and viability were unchanged, yet the number of CFU increased due to disruption of cell chains and biofilm aggregates. Carolacton had a limited effect on biofilm growth and mass, but reduced viability significantly. When incorporated into composite materials carolacton (25 μg/ml resp. 0.002%, w/w) had no adverse effect on physical/mechanical properties and retained its biofilm inhibiting effect. Life/Dead staining revealed a reduction of biofilm viability of up to 64%. CFUs were reduced by 98% and qPCR demonstrated a mean inhibition of 87%. In contrast, materials containing CHX or triclosan showed an insignificant effect on biofilm formation, even at a 100 fold increased concentration (0.2%). The anti-biofilm activity of composite material containing carolacton was stable over a period of 42 days.
  
  
  CONCLUSIONS
  Carolacton incorporated into dental filling material has a strong biofilm-inhibiting effect on S. mutans and is therefore potentially able to prevent secondary caries formation.
authors.affiliation: Department for Operative Dentistry, Periodontology and Preventive Dentistry, RWTH Aachen University, Germany. Electronic address: capel@ukaachen.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Apel
authors.forename: Andree
authors.initials: A
authors.lastname: Barg
authors.forename: Anke
authors.initials: A
authors.lastname: Rheinberg
authors.forename: Georg
authors.initials: G
authors.lastname: Conrads
authors.forename: Irene
authors.initials: I
authors.lastname: Wagner-Döbler
mesh_terms: D018441:Biofilms; D003764:Dental Materials; D018942:Macrolides / Q000494:pharmacology*; D013295:Streptococcus mutans / Q000187:drug effects* / Q000254:growth & development
chemical_list: D003764:Dental Materials; D018942:Macrolides; C553423:carolacton
keywords: Biofilm inhibition; Carolacton; Chlorhexidine; Dental composite; Secondary caries; Triclosan